Subject: Re: [RFC PATCH net-next v3 13/20] net: dsa: qca8k: make rgmii delay configurable

From: Andrew Lunn <[email-masked]>
Date: Wed, 5 May 2021 03:00:45 +0200

On Wed, May 05, 2021 at 12:29:07AM +0200, Ansuel Smith wrote:
> The legacy qsdk code used a different delay instead of the max value.
> Qsdk use 1 ps for rx and 2 ps for tx. Make these values configurable
> using the standard rx/tx-internal-delay-ps ethernet binding and apply
> qsdk values by default. The connected gmac doesn't add any delay so no
> additional delay is added to tx/rx.
> 
> Signed-off-by: Ansuel Smith <[email-masked]>
> ---
>  drivers/net/dsa/qca8k.c | 51 +++++++++++++++++++++++++++++++++++++++--
>  drivers/net/dsa/qca8k.h | 11 +++++----
>  2 files changed, 55 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
> index 22334d416f53..cb9b44769e92 100644
> --- a/drivers/net/dsa/qca8k.c
> +++ b/drivers/net/dsa/qca8k.c
> @@ -779,6 +779,47 @@ qca8k_setup_mdio_bus(struct qca8k_priv *priv)
>  	return 0;
>  }
>  
> +static int
> +qca8k_setup_of_rgmii_delay(struct qca8k_priv *priv)
> +{
> +	struct device_node *ports, *port;
> +	u32 val;
> +
> +	ports = of_get_child_by_name(priv->dev->of_node, "ports");
> +	if (!ports)
> +		return -EINVAL;
> +
> +	/* Assume only one port with rgmii-id mode */
> +	for_each_available_child_of_node(ports, port) {

Are delays global? Or per port? They really should be per port.  If it
is global, one value that applies to all ports, i would not use
it. Have the PHY apply the delay, not the MAC.

    Andrew